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drivers: counter: stm32: Add support for HSE as RTC clock source #46605

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drivers: counter: stm32: Add support for HSE as RTC clock source #46605

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15 changes: 15 additions & 0 deletions drivers/counter/Kconfig.stm32_rtc
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,14 @@ config COUNTER_RTC_STM32_CLOCK_LSE
help
Use LSE as RTC clock

config COUNTER_RTC_STM32_CLOCK_HSE
bool "HSE"
depends on SOC_SERIES_STM32F2X || SOC_SERIES_STM32F4X || \
SOC_SERIES_STM32F7X || SOC_SERIES_STM32H7X || \
SOC_SERIES_STM32L0X || SOC_SERIES_STM32L1X
help
Use HSE as RTC clock. An appropriate prescaler must be set.

endchoice #COUNTER_RTC_STM32_CLOCK_SRC

if !SOC_SERIES_STM32F4X
Expand Down Expand Up @@ -75,6 +83,13 @@ config COUNTER_RTC_STM32_LSE_BYPASS
help
Enable LSE bypass

config COUNTER_RTC_STM32_HSE_DIV
int "HSE prescaler"
depends on COUNTER_RTC_STM32_CLOCK_HSE
default 0
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@FRASTM FRASTM Aug 17, 2022 •
edited
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0 is not always the default, some stm32 devices like stm32F4 have a prescaler from 2 to 31 on the HSE clock, some others like the stm32wb or stm32L4/L5 have a fixed divider by 32 on the HSE clock

help
HSE division factor for obtaining a 1 MHz RTC clock

config COUNTER_RTC_STM32_BACKUP_DOMAIN_RESET
bool "Do backup domain reset"
default y
Expand Down
19 changes: 19 additions & 0 deletions drivers/counter/counter_ll_stm32_rtc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,11 @@ LOG_MODULE_REGISTER(counter_rtc_stm32, CONFIG_COUNTER_LOG_LEVEL);
#define RTC_EXTI_LINE LL_EXTI_LINE_17
#endif

/* Macro to fill up HSE prescaler values */
#define fn_hse_prescaler(v) LL_RCC_RTC_HSE_DIV_ ## v
#define hse_prescaler(v) fn_hse_prescaler(v)
#define LL_RCC_RTC_HSE_DIV_0 LL_RCC_RTC_NOCLOCK

struct rtc_stm32_config {
struct counter_config_info counter_info;
struct stm32_pclken pclken;
Expand Down Expand Up @@ -310,6 +315,16 @@ static int rtc_stm32_init(const struct device *dev)

LL_RCC_SetRTCClockSource(LL_RCC_RTC_CLKSOURCE_LSI);

#elif defined(CONFIG_COUNTER_RTC_STM32_CLOCK_HSE)

LL_RCC_SetRTC_HSEPrescaler(hse_prescaler(CONFIG_COUNTER_RTC_STM32_HSE_DIV));

/* Wait until HSE is ready */
while (LL_RCC_HSE_IsReady() != 1) {
}

LL_RCC_SetRTCClockSource(LL_RCC_RTC_CLKSOURCE_HSE);

#else /* CONFIG_COUNTER_RTC_STM32_CLOCK_LSE */

#if !defined(CONFIG_SOC_SERIES_STM32F4X) && \
Expand Down Expand Up @@ -396,6 +411,10 @@ static const struct rtc_stm32_config rtc_config = {
/* prescaler values for LSI @ 32 KHz */
.AsynchPrescaler = 0x7F,
.SynchPrescaler = 0x00F9,
#elif defined(CONFIG_COUNTER_RTC_STM32_CLOCK_HSE)
/* prescaler values for divided HSE @ 1 MHz */
.AsynchPrescaler = 0x7C,
.SynchPrescaler = 0x1F3F,
#else /* CONFIG_COUNTER_RTC_STM32_CLOCK_LSE */
/* prescaler values for LSE @ 32768 Hz */
.AsynchPrescaler = 0x7F,
Expand Down